96. Jahrestagung der Deutschen Gesellschaft für Pathologie e. V ...

Abstracts
a cell culture model. We mimicked ROS exposure of the epithelium in
human IBD using the non-tumor human colon epithelial cell line HCEC
and H2O2 as ROS.
Methods. The clinical course of IBD with multiple recurrences was simulated
by repeated H2O2 exposure cycles of the HCEC cell cultures. We
generated ten cell lines and confirmed neoplastic transformation by analyzing
them for clonal growth, enhanced proliferation, Colony Formation,
ROS-release, and β-galactosidase activity. The p53, Kras, and APC
mutation status, as well as microsatellite instability (MSI) were assigned.
Results. After three treatment cycles with H2O2, HCEC lost cell-cell
contact and started pilling up. Surviving HCEC showed uncontrolled
proliferation. Anchorage-independent growth in soft agar is often predictive
of tumorigenicity in vivo and is considered the most stringent
assay for malignant cell transformation in vitro. As ROS-injured HCEC
form colonies in soft agar, we concluded HCEC transformation. By
checking further hallmarks of cancer, we detected (i) self-sufficiency in
growth signals presumably via ROS-induced ROS-release, (ii) a limitless
replicative potential by overcoming cellular senescence, and (iii) evading
apoptosis. There were no alterations in p53, Kras, and APC gene, or MSI.
Conclusions. Our HCEC cell model provides novel insights into tumorinitiating
molecular events in IBD-associated carcinogenesis as these
cells are more likely to represent the potential target for tumor initiation
in vivo. Oxidative stress alone is sufficient to initiate HCEC transformation.
Transformed HCEC do not show well-known genetic alterations.
We therefore suppose early epigenetic changes to play an important role
in the initiation of the IBD-carcinoma pathway. This would further provide
the possibility of unravelling novel subsequent genetic alterations
that account for tumor initiation.
SO-003
Acetone compression and its impact on tumor staging of colorectal
cancer
J . Kitz1 , A . Gehoff2 , L .-C . Conradi3 , T . Sprenger3 , O . Basten4 , T . Liersch3 ,
P . Middel2 , J . Rüschoff2 1University Medical Center Göttingen, Department of Pathology, Göttingen,
2 3 Institute of Pathology Nordhessen, Kassel, University Medical Center Göttingen,
Department of General and Visceral Surgery, Göttingen, 4Institute of
Pathology Marburg, Marburg
Aims. Acetone compression (AC; Basten et al. Pathologe 2010) is a method
that allows for complete lymph node evaluation in colorectal cancer
(CRC), which is particularly important in rectal carcinomas pretreated
neoadjuvantly (Gehoff et al. Am J Surg Pathol 2011, accepted). In addition,
AC also facilitates detection of any further metastases in mesenteric
adipose tissue, e.g. perineural infiltration, which has its own prognostic
significance (Poeschl et al. JCO 2010). The present study deals with
the significance of AC for tumor staging of colorectal cancer. Not only
lymph node status but particularly also the significance of tumor cell
deposits and perineural infiltration are discussed.
Methods. A total of 245 specimens with CRC were analysed prospectively
via AC, half of which were rectal carcinomas. In consecutive cases (10–30
tissue samples each) the following parameters were evaluated: a. AC effect
on lymph node size and distribution of metastases in comparison
to preceding manual dissection on the same sample; b. The incidence of
metastatic spread to lymph nodes and as a tumor deposit or perineural
invasion in relation to the tumor location (distal, proximal and at the
level of the tumor).
Results. In the 245 tested specimens with colorectal cancer, a mean of
30 lymph nodes were assessed. There was no significant difference observed
between neoadjuvantly treated or untreated rectal carcinomas. The
main effect of AC was seen in lymph node size and metastatic status: In
the 10 manually dissected samples, the number of lymph nodes which
were